Nothing kicks off a dinner party better than a delicious appetizer, and these caramelized onion mushroom tarts is quite the showstopper. Squares of crispy puff pastry topped with sweet and sticky caramelized onions, mushrooms, and goat cheese. What’s not to love?
Caramelized Filling
While these aren’t the quickest appetizer to make, the patience needed is sooo worth it! Start by thinly slicing 2 white onions. Add them to a cast iron skillet with a drizzle of olive oil. Cook them over medium low heat for about 40 minutes. Yes 40! It sounds so long but it is worth it.
Once they onions are a medium caramel color, add in 8oz of roughly chopped baby bella mushrooms. The mushrooms will shrink a little, but still make sure there aren’t any large or wide pieces.
Also add 1/4 each of balsamic vinegar and brown sugar. Increase the heat slightly and simmer. Cook another 15 minutes or so, until the liquid from the mushrooms has evaporated and the vinegar is sticky and thick. You can make this filling ahead and store in the fridge until needed. I’d recommend a double batch! Use the extra to top burgers or steaks!
Making the Tarts
While making the filling, take a sheet of puff pastry out of the freezer and place on a floured surface. It takes about 40 minutes to defrost. Once defrosted, unfold the puff pastry and cut it into 9 equal squares. Use a fork to poke holes in on the squares (leave about a 1/4 in border of the dough with no holes). Spoon about one tablespoon of the onion mixture onto each square, spreading close to the edges.
Transfer the tarts to a baking sheet lined with parchment, and top each tart with a bit of crumbled goat cheese. Beat together an egg and 1 tablespoon of water and use a pastry brush the egg wash on the edges of each square. This is key to helping get a nice golden brown!
Bake in a 400 degree oven for 15 minutes or until golden brown, sprinkle with chopped parsley, cool slightly and serve!
They seem so fancy, but these caramelized onion mushroom tarts are actually not difficult to make! Puff pastry makes everything better, and with just a little patience, you have yourself a delicious appetizer.
Need Other Appetizer Ideas?
- Lemon Herb Whipped Ricotta Dip
- Philly Cheesesteak Egg Rolls
- Sausage Stuffed Sweet Peppers
- Beer Cheese Sauce
Caramelized Onion Mushroom Tart
Ingredients
- 1 tbsp olive oil
- 2 medium white onions thinly sliced
- ½ tbsp unsalted butter
- 8 oz baby bella mushrooms roughly chopped
- ¼ cup balsamic vinegar
- ¼ brown sugar packed
- salt and pepper to taste
- 1 sheet puff pastry defrosted
- 1 large egg
- 1 tbsp water
- 4 oz goat cheese crumbled
- 1 tbsp fresh parsley chopped
Instructions
- Place onions and oil in cast iron pan over medium-low heat. Stir occasionally for approximately 40 min or until onions are light caramel in color.
- Add butter, roughly chopped mushrooms, vinegar, and sugar to pan. Heat to a simmer and cook an additional 10-15 minutes until most of the moisture has evaporated. Season with salt and pepper to taste.
- Preheat the oven to 400°
- Cut one sheet of puff pastry dough into 9 equal squares. Using a fork, poke holes in the center of each sheet, avoiding 1/4 in border of the dough.
- Place about 1 tbsp of the onion mushroom filling in the center of each dough square, spreading close to the edges.
- Transfer the squares to a baking sheet lined with parchment and crumble a little bit of goat cheese on top of each.
- Use a fork to scramble together the egg and water. Using a pastry or basting brush, brush the 4 edges of each square with the egg wash. This will help them brown.
- Place the baking sheet in the oven to cook for 15 minutes or until the edges are golden brown.
- Sprinkle with fresh parsley and serve hot or room temperature.
